Abstracts from Hydrocephalus 2022: the Fourteenth Meeting of the Hydrocephalus Society

Introduction


Introduction:
The assessment of craniospinal compliance (CC) is relevant for the diagnosis of idiopathic normal pressure hydrocephalus. To that end, invasive volume loading methods are required. Recently, a novel apparatus measuring non-invasively variations of head dielectric properties during cardiac and respiratory cycles has been proposed as the derivation of CC surrogates. Here, we investigate the effect of tilting on the electrical signal (referred to as W in the following) acquired with this apparatus. Methods: Nineteen young (age: 25 ± 2 years) healthy subjects participated in this study. To measure W, two isolated electrodes were placed on the subjects' forehead, in areas corresponding to the F3, F7 and F4, F8 electrodes in a 10-20 electroencephalogram setup. The protocol consisted of 10 min in supine horizontal position followed by 5 min at the tilt angles + 75°, 0° (control) and -30°. The peak-to-valley amplitude of W related to cardiac modulation (AMP) was computed. Results: In all volunteers, characteristic cardiac and respiratory oscillations were observed in W. AMP decreased during head-up tilting (0°: 100%; + 75°: 80 ± 17%, P = 0.002). After returning to its resting state value during the control period (0° control: 95 ± 11%, P = 0.12), AMP increased during head-down tilting (-30°: 148 ± 36%, P < 0.001). Conclusions: Tilting alters the distribution of CC between cranial and spinal compartments. We consider AMP changes during tilting to reflect partially the different intracranial volume variations taking place at the tested angles. Therefore, our results warrant further studies for investigating the potential of this non-invasive method to derive CC surrogates.
Introduction: Normal pressure hydrocephalus (NPH) is a treatable cause of gait and cognitive decline that can be challenging to diagnose. We hypothesized that unsupervised machine learning can use patterns of cerebrospinal fluid (CSF) distribution to differentiate NPH patients from controls and to distinguish between NPH phenotypes. Methods: 104 patients with NPH and pre-shunt MRI and 104 ageand sex-matched controls were included. 20 patients and controls were held out as a test set. MPRAGE sequences were segmented and normalized to the Mayo Clinic Adult Lifespan Template (MCALT). Independent component analysis (ICA) was performed on the CSF segmentation maps. Visual grading of MRIs was done for markers of disproportionately enlarged subarachnoid space hydrocephalus (DESH): high convexity-tight sulci (HCTS), enlarged sylvian fissures (ESF), and ventriculomegaly. Participants were divided into four phenotypes: congenital (ventriculomegaly and diffusely narrow sulci), DESH (HCTS + ESF), HCTS only, and no HCTS. Results: We identified 7 patterns of CSF distribution based on optimal ICA decomposition. These patterns appeared to capture clinically relevant CSF features. High weights on patterns with abundant CSF in the Sylvian fissures and lower CSF at the high convexity were predictive of NPH, and in particular the DESH and HCTS phenotypes. The congenital subgroup had higher weights on a pattern capturing all CSF spaces. The accuracy of automated NPH diagnosis vs. clinical was 92.2%/87.5% for train/test. Conclusions: Data-derived patterns of CSF distribution allowed for high accuracy in diagnosing NPH. Different phenotypes were associated with different weights across patterns.

Intrauterine spontaneous subdural hematoma with hydrocephalus
Mohammed Nooruldeen Jabbar Canadian Specialist Hospital -Dubai, UAE. Correspondence: Dr Mohammed Nooruldeen Jabbar (mohammed. nooraldeen@yahoo.com) Fluids and Barriers of the CNS 2022, 19(1) Introduction: Subdural hematoma in a new born baby is associated with a history of maternal trauma, complicated vaginal delivery, instrumental delivery, foetal/maternal thrombocytopenia, coagulopathy, hepatic disease, infection or using drugs during the pregnancy; but in the absence of the above, intrauterine subdural hematoma is a rare event. Methods: We present a new born delivered to a healthy mother at 38 weeks by elective caesarean section after he had been diagnosed with macrocephaly by routine obstetric growth scan ultrasound at 35 weeks of gestational age. The baby's APGAR score was 4 at 1 min, he was pale, his fontanel was tense and his Occipitofrontal circumference was 46 cm, therefore, he was intubated immediately and transferred to Neonatal Intensive Care Unit. Brain Computed tomography revealed huge right sided subacute subdural hematoma that was almost occupying the entire right hemicranial space and severely compressing the underlying brain tissue. In addition, there was marked dilatation of the left lateral ventricle. Results: The subdural hematoma was evacuated by two burr holes surgery, followed by repeated subdural tap. Intraventricular haemorrhage treated by repeated ventricular tap until Cerebrospinal Fluid became clear, then ventriculoperitoneal shunt surgery was done for him. The baby was discharged from the hospital in stable condition and he is on continues follow up in outpatient clinics. Conclusions: Spontaneous intrauterine subdural hematoma with hydrocephalus is a rare cause of macrocephaly that could be treated by good cooperation among obstetrician, neonatologist and neurosurgeon, but needs more study to find the cause of this condition so we can prevent its occurrence.
Introduction: ICP changes with body position. The exact details of the change and the underlying mechanisms are not fully understood. Understanding the exact change could inform management of patients with CSF dynamics disturbances, as well as provide information needed to design a smart shunt. Methods: Single-centre, prospective cohort study. Patients undergoing continuous intraparenchymal intracranial pressure (ICP) monitoring were fitted with continuous position sensors and underwent a set sequence of movements including sit-stand transitions for set periods of time. ICP and postural data were recorded at 100 Hz and synchronised. Data were analysed for ICP and pulse amplitude (PA) as well as wave form changes during actual movement. The effect of shunting and various pathologies was explored. Results: 49 patients (male = 14; mean age 43 ± 14) were recruited. 15 patients had shunts. The average change in ICP from sitting to standing was 1.9 ± 8.9 mmHg and the average change in PA was 0.0 ± 4.7 mmHg. There was a transient pressure wave which occurs at the time of movement. The average magnitude of this wave during sitting to standing transitions was 4.9 ± 4.3 mmHg and during standing to sitting transitions this was 4.3 ± 3.8 mmHg. We present the effect of shunting and pathological conditions. Conclusions: ICP increases slightly when we stand from sitting position. Transitioning between sitting and standing position creates a transient wave in ICP which then returns to a similar pre-movement ICP. This differs from other movement transitions.
Introduction: While the influence of the cardiac cycle on intracranial pressure (ICP) is well documented, the relationship between ICP and other physiological parameters remains less certain. We explore the effect of three interventions on ICP: (i) deep breathing, (ii) mindful attention and (iii) visual biofeedback, all considered to alter respiratory and/or cognitive function. Methods: A single-centre prospective, pilot study was performed in adult patients undergoing 24-h ICP monitoring for suspected CSF dynamic disorders. A baseline reference was established for each patient, in which the patient was asked to sit comfortably without a task (6 min). Following a practice period, the three interventions (3-min each) were performed with a 2-min rest interval in between, and the experiment was repeated. A linear, repeated-measures mixedeffects analysis was carried out with heart and respiratory rate as fixed confounders and each patient as a random-effects variable, with each intervention compared against the baseline. Results: Four patients were analyzed (3 females, mean age = 39.3 years [SD ± 28.7]). At baseline, the group average ICP was -0.35 mmHg (SD ± 2.07). After accounting for confounders and patient-level differences, deep breathing was independently associated with an ICP decrease of 0.88 mmHg (p = 0.07), mindful attention: Fluids Barriers CNS (2022) 19:104 a reduction of 1.29 mmHg (p = 0.02), and visual biofeedback: a reduction of 1.27 mmHg (p = 0.01). Aggregate, univariate comparisons demonstrated matching relationships and significance levels. Conclusion: This study represents the first to investigate the effects of simple, physiological interventions, which can independently reduce ICP. Further, large-sample work is warranted to explore the mechanisms through which these effects are mediated.
Experimental investigation of the influence of pathological blood dynamics on the CSF system with regard to normal pressure hydrocephalus Anne Benninghaus 1 , Florian Huber 1 , Alexander Müller 1 , Klaus Radermacher 1 1 Chair of Medical Engineering, RWTH Aachen University, Germany Correspondence: Anne Benninghaus (benninghaus@hia.rwth-aachen. de) Fluids and Barriers of the CNS 2022, 19(1) Introduction: It is known that often the supplying arteries stiffen with age. In addition, increased pressure in the venous system has been measured in patients with Normal Pressure Hydrocephalus (NPH). The impact of these changes on cerebrospinal fluid (CSF) dynamics has not been analysed. Therefore, the aim of this study was to experimentally investigate the influence of age-related and pathological changes in blood dynamics on CSF dynamics to examine whether they contribute to the pathogenesis of NPH. Methods: For sensitivity analysis, a validated in vitro model was used to alter parameters of blood dynamics while recording intracranial pressure (ICP) and cervical CSF flow. The investigated parameter settings, based on literature data, are an increase in stroke volume (SV) by 20-30%, a decrease in total cerebral blood flow (tCBF) by 10-30% and a decrease in arteriovenous delay (AVD) between 40 and 60%. Results: The ICP amplitude increases with an elevation in SV and decreases with a reduction in tCBF and AVD. The spinal CSF flow also increases with elevated SV and decreases with a reduction in tCBF and AVD. Conclusions: Increased ICP amplitudes and decreased cervical CSF flow are typical characteristics of patients with NPH. However, none of the parameter settings could induce both characteristics simultaneously. Thus, the parameters may favour the development of NPH, not as a single factor, but rather as a combination of several factors. In addition to the referred blood parameters, these include cranial and spinal (dynamic) compliance, resorption and flow resistance.
Postoperative valve pressure adjustment for a long-term success following shunt in idiopathic normal pressure hydrocephalus F. Torregrossa 1 , G. Grasso 1 1 Neurosurgical Unit, Department of Biomedicine, Neurosciences and Advanced Diagnostics (BiND), University of Palermo, Italy Correspondence: Fabio Torregrossa (fabiotorregrossa00@gmail.com) Fluids and Barriers of the CNS 2022, 19(1) Introduction: The standard treatment for idiopathic normal pressure hydrocephalus (iNPH) is surgical cerebrospinal fluid (CSF) diversion, most commonly through implantation of a ventriculoperitoneal shunt (VPS), to alleviate the typical symptoms related to this condition. The development of programmable-pressure shunt valve devices has reduced the major complications associated with the CSF drainage volume and appears to have increased shunt effectiveness. However, optimal valve pressure is crucial since, over time, symptoms can occur, especially gait can worsen following an initial improvement. Methods: We describe our experience based on the observation of a cohort of 74 patients operated by VPS in whom modification of the valve range has been performed in a strict follow-up performed at 3, 6, and 12 months postoperatively and yearly thereafter for at least 10 years. Results: Among 84 patients treated, changes in valve pressure were performed in 42 patients (51.2%). Pressure changing has been performed in 7 cases (16.7%) at 3 months, in 22 (52,3%) at 6 months, 7 (16.6%) at 1 year, and in 6 cases (14.3) at 2 years follow-up. Revisions resulted in clinical improvement in 94% of cases, especially in gait disturbance compared to the other symptoms. Conclusions: Surgical treatment for iNPH by VPS is a safe modality able to improve symptoms in most affected patients even in the long term. Symptoms recurrency can be managed by valve range modification. This management, in our experience, has shown to improve quality of life and better long-term independent living expectations.  (1) Introduction: Dimethyl sulfoxide (DMSO) is a commonly used pharmaceutical for skeletal, urological, and inflammatory problems, and is also considered a universal solvent. It can efficiently dissolve both polar and nonpolar compounds. However, its neurotoxicity has not been studied. In a serendipitous finding, we discovered that DMSO induces hydrocephalus when injected into the ventricles. We hypothesized that DMSO's high affinity to water induces an active diffusion of parenchymatic fluid into the ventricles through the water channel aquaporin 4 (AQP4). Methods: In vitro and in vivo experiments were performed to quantify fluid extravasation through perivascular AQP4. For in vivo experiments, DMSO was injected intraventricularly into two days old C57BL mice. In vitro experiments used 24 transwell plates with confluent brain endothelial cells from mice. Results: Our results showed dose-dependent ventriculomegaly associated with DMSO intraventricular injection. The ventriculomegaly increased proportionally when 1, 3, or 5 ul/g of DMSO was injected into the ventricles and was attributed to fluid extravasation from the parenchymatic vessels to the ventricular system. In vitro experiments confirmed DMSO's -dependent permeability through brain endothelial cells. Conclusions: When injected into the ventricles of C57BL mice in the perinatal period, DMSO induces hydrocephalus. This is a newly discovered etiologic agent for the development of hydrocephalus. This finding should be considered when administrating pharmaceuticals with DMSO in pediatric patients.

Introduction:
Normal Pressure Hydrocephalus is a disease directly related to the change in brain compliance and consequent repercussions in the brain parenchyma. Invasive monitoring of parameters such as compliance and intracranial pressure proves to be reliable, especially for the prognosis in neurocritical patients. The present study proposes to observe the parameters obtained in a non-invasive sensor for monitoring intracranial compliance from the company Brain4care ® in patients with suspected NPH and compare with the tap test result. Methods: Twenty-eight patients submitted to the Tap test were evaluated, consisting of medical, radiological, physiotherapeutic and neuropsychological evaluations before and after puncture of 50 ml of CSF, as well as evaluation by the Brain4care ® non-invasive intracranial compliance measurement device in the following positions: lying, sitting and standing, both statically and for 05 min each before and after lumbar puncture. The tap test result was compared to the time to peak and P2/P1 ratio parameters obtained by the device. Results: Our results show that in the group where the Tap test was positive, there was a median P2/P1 ratio greater than 1.0, indicating a change in brain compliance. In addition, there was also a significant difference between patients with positive, negative and inconclusive results, especially in the lying position. Conclusion: The non-invasive intracranial compliance device when used in patients lying down and standing up obtained parameters that suggest correspondence with the tap test result.

Background:
We previously reported that the apparent diffusion coefficient (ADC) obtained from diffusion MRI in the cerebral white matter significantly changed during the cardiac cycle, and this change (del-taADC) aided in the diagnosis of iNPH. It is unclear how deltaADC is associated with the CSF tap test response in "possible iNPH. " Method and Materials: This study included 22 patients with possible iNPH who either showed symptomatic improvements (positive group, n = 17) and those without improvement (negative group, n = 5) after the CSF tap test. On a 1.5-T MRI, ECG-triggered single-shot diffusion echo planar images were obtained. The deltaADC was calculated from the maximum-minus-minimum ADC value of all cardiac phase images on a pixel-by-pixel basis. Then, the deltaADC, the mean ADC during the cardiac cycle (ADCmean), and the rates of change before and after CSF tap test of the white matter were determined and compared between positive and negative groups in possible iNPH. Results: Before the CSF tap test, the deltaADC in the positive group was significantly higher than that in the negative group (P < 0.05), but there was no significant difference in the deltaADC between positive and negative groups after the CSF tap test. No significant difference was observed in the ADCmean between positive and negative groups both before and after the CSF tap test. The deltaADC change rate before and after CSF tap test in the positive group was significantly higher than that in the negative group (P < 0.05), but there was no significant difference in the ADCmean change rate before and after CSF tap test between positive and negative groups. Introduction: With the increasing number of patients with normal pressure hydrocephalus (NPH) identified, there is an urgent need to explore the pharmacological treatment of NPH. Clinical experience and research all have evidence that acetazolamide (AZA) can reduce the production of cerebrospinal fluid (CSF), but it is less used because of its side effects. Methazolamide (MTZ), similar in structure to AZA, has the advantages of high lipid solubility, easy penetration through the blood-brain barrier, and potential neuroprotective effects. Therefore, MTZ may be superior to AZA and become one of the effective methods in treating NPH. First, this study aimed to investigate the efficacy and safety of oral MTZ in patients with NPH to provide an alternative treatment for some inoperable NPH patients. The objective is to study the efficacy and safety of MTZ for the treatment of NPH patients. Methods: A randomized, double-blind, placebo-controlled, prospective clinical study was conducted in Aviation General Hospital. A total of 35 NPH patients including 29 idiopathic normal pressure hydrocephalus (iNPH) and 6 secondary normal pressure hydrocephalus (sNPH) received drug treatment in our hospital from September 2019 to March 2021.All patients were unsuitable for or refused surgical treatment for some reasons. The patients were divided into drug group (n = 18) and control group (n = 10), taking oral MTZ or placebo 25 mg twice daily, increasing to 50 mg twice daily after 1 week if there was no discomfort. The 10 m gait score, cognitive function score, brain MRI check were completed before and 1 month after oral administration. The assessment of idiopathic normal pressure hydrocephalus scale (iNPHGS) score was performed 1 month and 3 months after Fluids Barriers CNS (2022) 19:104 oral administration. The primary efficacy endpoint was iNPHGS score for 3 months treatment and the secondary efficacy endpoint was the assessment of above scales for 1 month treatment. Results: As compared with baseline, the effect of 1 month treatment showed that MOCA scores [(16.2 ± 8.8) and (14.8 ± 8.7) scores, t = --2.68, P = 0.02], 10 m gait scores [(22.3 ± 11.2) and (25.6 ± 12.9), t = 2.76, P = 0.02], iNPHGS scores [(7.3 ± 3.2) and (8.1 ± 3.5), t = 4.08, P < 0.01] were improved. The effect of 3 month treatment showed that the iNPHGS score (6.1 ± 2.4) was improved compared with baseline (t = 5.07, P < 0.01) and 1 month (t = 4.11, P < 0.01). But the above scores of the control group were not significantly improved compared with the baseline (all P > 0.05). After 1 month treatment, the 10 m gait score and iNPHGS score in the drug group were improved compared with those in the control group (all P < 0.05). After 3 months treatment, the iNPHGS score was improved compared with the baseline level in the control group (t = − 4.41, P < 0.05). The above 35 patients had no serious adverse reactions such as hypokalemia and acidosis. There was no significant difference in adverse events between the two groups (χ2 = 0.01, P = 1.00). Conclusions: The treatment of MTZ could effectively improve the clinical symptoms of NPH patients with good safety. Introduction: An ideal shunt for hydrocephalus treatment must maintain intracranial pressure within normal limits, drain the cerebrospinal fluid (CSF) without creating symptoms of over drainage independent of body position/physical activity, and present a long-lasting solution without reoperation. All these criteria can be met by shunting CSF to the venous intracranial sinus. However, previous studies in this field have seen the drain outlet in the sinus become occluded. This study investigates an outlet designed to drain without occlusion or thrombus formation. Methods: Patients diagnosed with hydrocephalus are shunted with a standard ventricular drain, low pressure uni-directional valve and the investigational outlet at the jugular foramen/sigmoid sinus. The outlet collapses into a standard introducer, placed using standard intravascular techniques. The outlet is held in the middle of the vein by a nitinol distancer, preventing it from touching the wall of the vein. Shunts are tested for patency at 3 months and at 6 months by water column test. Results: As of May 2022, 12 patients have been operated, with 6 past the 6-month endpoint. All shunts were patent at follow-up, and clinical effect satisfactory. No subdural effusion or haematomas were detected. No occlusions of the sigmoid sinus or jugular vein were observed. No signs of lung emboli. Conclusions: Initial results are promising: the nitinol frame prevents outlet occlusion without provoking thrombosis. The shunt remains open, indicating better than average shunt survival. This study represents an important first step in proving that shunting to the cranial sinus is a safe, simple and long-lasting solution.
The utility and reversibility of MRI biomarkers in predicting raised intracranial pressure Musa China 1 , Anand S. Pandit 2 , Hasan Asif 2 , Linda D' Antona 2 , Shivani B. Joshi 1 , Raunak Jain 1 , Crystallynn Skye The 1 , Arif H.B. Jalal 1 , Zakee Introduction: Intracranial pressure (ICP) typically requires invasive monitoring for accurate measurement. Non-invasive MRI biomarkers, including morphology of the pituitary, optic nerves and globe, are a useful tool in the identification of patients with raised ICP. We aim to determine the utility of brain MRI biomarkers in determining pathological ICP levels and their reversibility following CSF diversion. Methods: A single-centre, retrospective cohort study. 327 patients (227 Female) underwent ICP monitoring with recent MR-imaging. Diagnoses included IIH (25%) and Chiari (8%). 5 MRI biomarkers were assessed: T1-sagittal views for pituitary: sella volume (Yuh grade), optic nerve vertical tortuosity and T2-axial views for optic nerve sheath distension (ONSD), posterior globe flattening (PGF) and optic disc protrusion (ODP). Results: Median ICP for normal and abnormal sella morphologies were 3.73 and 7.04 mmHg, respectively (p < 0.05); normal and abnormal VT were 4.52 and 7.04 mmHg (p < 0.05); abnormal PGF were 4.51 and 10.35 mmHg respectively (p < 0.05). A baseline logistic model using all radiological parameters with age and sex as confounders predicted abnormal ICP with an AUC = 0.6857, sensitivity of 0.90 and specificity was 0.35. Pituitary Yuh grade and PGF were independently associated (p < 0.05, following multiple comparison correction). Furthermore, we found that pituitary sella grading and optic nerve VT were associated with significant pairwise reversibility (p < 0.05), following CSF diversion. Conclusions: Specific radiological features are promising non-invasive markers associated with intracranial hypertension and also demonstrate reversibility following CSF diversion. Non-invasive MRI imaging can play a more significant role in the diagnostic workup of patients with possible CSF dynamic abnormalities.

Introduction:
There is no pharmacological treatment alternative for patients with idiopathic normal pressure hydrocephalus (iNPH). The aims are to investigate if the carbonic anhydrase inhibitor acetazolamide given to patients with iNPH improves gait function and to study the pathophysiological mechanisms leading to reduced symptoms. Methods: Double-blind, randomized, placebo-controlled trial at a single center with the intent to include 50 patients. Randomization to placebo or acetazolamide 250 mg twice daily with treatment duration from diagnosis (baseline) to admission for shunt surgery. Primary outcome will be change in gait between study visits, measured with a combined score of 10 m gait test, timed-up-and go test and 3 m backwards walk. Biomarkers of neurodegeneration and brain injury will be measured in plasma and intraventricular CSF. MRI of the brain including Synthetic MR and perfusion sequences will be performed before and after treatment in a subgroup of 24-26 patients.

Introduction:
Paraspinal muscles play an important role in gait. This study aimed investigate whether the degenerative state of lumbar paravertebral muscles assessed by magnetic resonance imaging (MRI) in terms of the volume status and fatty degeneration could be related to the gait improvement after shunt surgery in NPH. Methods: This is a retrospective analysis of 30 patients with NPH who underwent lumboperitoneal shunt surgery. The volume status and fatty degeneration of lumbar elector spinae muscles, multifidus muscles and psoas major muscles were measured by T2 weighted axial MRI at L2-3-4. The Timed Up and Go (TUG) test was performed to measure gait changes. The correlation between the status of paraspinal muscles and the gait improvement after shunt surgery in NPH was analyzed. Results: Correlation analysis showed the significantly negative correlation between the psoas muscle index and the gait improvement after shunt surgery (r = − 0.280, p = 0.036). The fat infiltration rate of multifidus muscles in the poor improvement group was significantly higher than that in the better improvement group (p < 0.05). Conclusions: Qualitative evaluation of the paraspinal muscles has the potential to reflect the gait prognosis after shunt surgery in normal pressure hydrocephalus.  (1) Introduction: Programmable valves provide an equal or superior neurological outcome when compared to fixed pressure ones, with fewer complications, in treating iNPH. Long-term costs of these treatments have not been properly compared in literature. The authors sought to compare efficacy, safety and costs of one-year treatment of iNPH patients with a novel programmable valve (Sphera Pro ® ) with gravitational unit and a fixed pressure valve. Methods: A prospective cohort of iNPH patients treated with programmable valve (G1) was compared to a historical cohort of iNPH patients treated with fixed pressure (G2). Our primary outcome was the mean cost of treating iNPH up to one year. Cost variables assessed included number of surgeries, length of ICU and hospital stay, and number of imaging tests. Efficacy in treating iNPH, measured by mean NPH Japanese Scale, and safety, measured by complications rates, were assessed as secondary outcomes. Results: A total of 19 patients were analyzed in each group. Comorbidities and clinical presentation were similar between groups. Both G1 and G2 patients had neurological improvement over time (p < 0.001), but no difference was seen between groups. G2 had more complications than G1 (52.6% vs 10.5%, p = 0.013). Annual treatment cost per patient was US$ 3820 ± 2231 in G2 and US$ 3108 ± 553 in G1. Mean difference was US$712 (95% CI, 393-1805) in favor of G1. Conclusion: The Sphera Pro ® valve with gravitational unit had oneyear treatment cost not higher than that of fixed-pressure valve, and resulted in similar efficacy and fewer complications.

Outcomes following endoscopic third ventriculostomy in adults
Suhaib Abualsaud 2 , Sebastian Yim 1 , Joseph Phoenix 1 , Marian Byrne 2 , Aimee Goel 2 , Luke Galloway 2 , Yasir Chowdhury 2 , Georgios Tsermoulas 2,3  (1) Introduction: ETV success score is frequently used to predict outcomes following ETV in adult patients, however this was a model developed for use in paediatric patients who often present with different causes of hydrocephalus compared to adults. We present a 9-year series of adult patients at a single tertiary Neurosurgical centre undergoing ETV for hydrocephalus to identify predictive factors in the adult population. Methods: A retrospective study design was used to analyse 136 patients who underwent ETV between 2012 and 2020. Observed ETV success was compared to pre-operative predicted ETV success scores. A multivariable Bayesian logistic regression analysis was used to determine the factors that best predicted ETV success in our cohort of patients. Results: Overall ETV success rate was 77%. Observed ETV success corresponded well with predicted ETV success using the ETV success score for the higher scores 80 and 90, but less well for lower scores. Aqueductal stenosis and a planned versus unplanned procedure were predictive of ETV success, whereas age, aetiology of tumour and location of CSF pathway obstruction other than aqueductal did not influence ETV success. Conclusions: ETV was successful in approximately three quarters of adult patients with hydrocephalus. Obstruction at the level of the aqueduct of any aetiology is a predictive factor for ETV success. Age and other locations of obstruction have no bearing on ETV success. ETV success score is less reliable in the lower score categories, and there is a need for the development of ETV predictive tools more specific to adults.

Psychiatric signs and symptoms in idiopathic normal pressure hydrocephalus (iNPH): a systematic review and meta-analysis
Clara Belessiotis-Richards 1 , Esha Abrol 1 , Ahmed Toma 2 , Eileen Joyce 2 , Gill Livingston 1 1 University College London, London, UK; 2 National Hospital for Neurology and Neurosurgery (NHNN), Queen Square, London, UK Correspondence: Clara Belessiotis-Richards (c.belessiotis@ucl.ac.uk) Fluids and Barriers of the CNS 2022, 19(1) Introduction: The aim was to conduct a systematic review and metaanalysis of the psychiatric signs and symptoms in people with probable or possible idiopathic normal pressure hydrocephalus (iNPH), and estimate their prevalence. Methods: We searched PUBMED/MEDLINE, Embase, Cochrane, Psy-cINFO and CINAHL from inception to search date, without language or study type restriction, including only peer-reviewed publications. We extracted key descriptive data including author, year, country, setting, participant number, age, sex, study design, diagnostic tool, classification of iNPH, timing of assessment, follow-up time, comparison group, number of cases, response rate. Outcome data included proportion of patients with symptoms or signs. We used I 2 to assess heterogeneity and random effects meta-analysis to calculated pooled estimates. Results: Our preliminary results found a pooled prevalence of 70% for apathy, 19% for anxiety, 19% for delusions, 6% for hallucinations, 21% Fluids Barriers CNS (2022) 19:104 for disinhibition, and 35% for agitation in iNPH. Our results for depression could not be meta-analysed due to heterogeneity; prevalence of depressive symptoms ranged from 8 to 56% across studies. Conclusions: iNPH is associated with high rates of neuropsychiatric symptoms and signs. More work needs to be done to describe these and their response to treatment.

Introduction:
Cognitive impairment is a key characteristic of idiopathic normal pressure hydrocephalus (iNPH) and may improve following cerebrospinal fluid (CSF) diversion. Neuropsychological tests can be used to aid diagnosis and assessment. The objective of this study was to assess the utility of these tests in patients undergoing CSF drainage. Methods: A retrospective review was conducted of consecutive patients undergoing CSF drainage for suspected iNPH through a dedicated multidisciplinary (MDT) clinic. All patients underwent either high volume lumbar puncture (LP) or extended lumbar drain test (ELD) and had a repeatable battery of neuropsychological testing in memory, attention, motor speed, language, and executive function, along with a 10-m gait assessment. Following MDT evaluation, patients considered to be 'responsive' were offered a ventriculoperitoneal shunt. Results: A total of 26 (15 male, 11 female, mean age 74 years) patients underwent CSF drainage with 20 (77%) demonstrating a positive response (13 following ELD and 7 following LP). Of the cognitive tests undertaken pre and post drainage, there was significant improvement in RBANS Immediate Story Recall (pre = 10.68, post = 13.21, p < 0.05), and Delayed Story Recall (pre = 3, post = 4.1, p < 0.05) but no significant change in WMS-III Mental Control, Trail Making Task (1) Objective: The sensitivity of the spinal tap test (STT) for the diagnosis of a normal pressure hydrocephalus (NPH) is low. This may be due to insensitive tests, which are applied to prove the diagnosis. Often patients notice an improvement despite no change in the tests. Aim of this study is to show if subjective improvement only is sufficient for the diagnosis of NPH and consequently for the indication of a hydrocephalus shunt. Methods: Patients after the STT were evaluated with objective gait tests and a questionnaire, where they had to log in their subjective gait changes regularly for a whole week. All patients who had an objective or only a subjective improvement got a ventriculo-peritoneal shunt. A follow-up was done between 1 and 3 years via a telephone interview. Results: 86 patients who were evaluated with a STT. 52 showed an objective, 34 only a subjective improvement. All patients were shunted. Medium follow-up was 22 months. 77% (40 of 52) of the patients with objective improvement after STT showed a permanent improvement, whereas 82% (28 of 34) of patients improved with only subjective improvement after STT. Conclusion: These results show, that subjective improvement alone after STT is as good as objective improvement for the diagnosis of NPH and for shunting. Therefore, using subjective improvements alone after STT may increase the sensitivity of STT for the diagnosis of NPH and for the indication for shunting.  (1) Introduction: iNPH is a primitive, progressive and partially reversible form of dementia with cognitive deficits in different domains (attention/orientation, memory, fluency, language and visuospatial abilities). Early treatment improves the outcome and suggests the importance for reliable diagnostic markers that accompany neuroradiological parameters and CSF dynamics invasive evaluations. The purpose of this exploratory study is to quantify the cognitive status of patients both before and after infusion and tap test. Methods: From January 2020, neuroradiological, neuropsychological, CSF dynamic and tap test results of forty-one subjects were prospectively collected. Basic demographic data on age and sex were recorded at the point of referral. Evans' index, callosal angle and DESH features were calculated on MRI sequences. R out , P plateau and P opening , and neurological and neuropsychological response to deliquoration were collected. To quantify cognitive modifications after the test, we used Addenbrooke's Cognitive Examination Revised (ACE-R) battery. Results: The mean age of the population was 77.3 ± 5.5 years. Fourteen females and twenty-seven males composed the cohort. All patients demonstrated a statistically-significant impairment in all ACE-R domains before the test. Among the sub-test of the ACE-R, we founded a statistically-significant amelioration after the tap test for orientation (p = 0.019), indirect recall (p = 0.039) and naming (p = 0.018). We documented a significant correlation between P plateau and posttest orientation (p = 0.017) and post-test naming (p = 0.009). P opening value positively correlated with naming performance after the test (p = 0.037). Conclusions: In our iNPH cohort, the ultra-fast battery demonstrated rapid neuropsychological changes, characterized by a statistically-significant improvement in orientation, naming and indirect recall after CSF subtraction. Introduction: Prominent cognitive deficits in iNPH include processing speed, psychomotor speed, attention, and executive functioning. To facilitate cognitive assessment in routine practice, we sought to develop a brief cognitive screen and monitoring tool and assess the feasibility of its implementation. Methods: Based on a systematic literature review, tests encompassing key deficits observed in iNPH were selected. These include validated tests completed by the patient (ACE-III, WAIS-IV Symbol Search, TMT-A, TMT-B, GAD-7, PHQ-9, WHO-QoL BREF and AES) and an informant (CBI-R). A convenience sample of patients and their clinicians rated acceptability and feasibility dimensions using visual analogue scales (0-10).

Assessment of cognition and psychological wellbeing in adults with idiopathic normal pressure hydrocephalus (iNPH)
Results: Twelve patients attending a multidisciplinary iNPH clinic prior to treatment completed the battery. Administration took approximately 25 min. Most patients found the assessment enjoyable (92%) and of appropriate duration (83%), and were satisfied to be re-assessed in the future (100%). All clinicians (n = 3) found the battery clear, easy to administer, and time-efficient. Patients displayed deficits in attention, executive functioning, psychomotor and processing speed. Six patients scored below the ACE-III cut off for dementia. Patients reported low quality-of-life in at least three domains. There was considerable inter-patient variability in self-reports of anxiety, depression, and apathy. Conclusions: Evidence-based, cost-effective assessment of cognition and psychological wellbeing in iNPH can inform diagnosis and monitor treatment outcomes. Preliminary data indicates the battery is sensitive to cognitive impairment, captures the specific cognitive changes observed in iNPH, and helps identify inter-patient variability enabling bespoke support. The battery was acceptable to patients and clinicians in a routine practice setting. Study supported by: Revert Project, Interreg, France (Channel Manche) England, funded by ERDF.
Introduction: This study evaluated the changes of thyroid hormones in iNPH patients before and after the ventriculoperitoneal shunting. We also sought to ascertain whether shunt implantation would result in the improvement of thyroid function and depression and anxiety. Methods: Serum levels of FT3, FT4 and TSH were analysed among iNPH patients preoperatively, postoperatively and 3-months after the ventriculoperitoneal shunting. Preoperative FT3/FT4 ratio and its effect on outcome measured by PHQ-9 and GAD-7 preoperatively and 3-months after the shunting were analysed. Results: 25 patients were included (52% women, mean age 63.5(SD9.5) years. Median Evan's index was 0.42 (range 0.34-0.56). Preoperative Evan's index was related to FT3 (r = 0.504, p = 0.017). The median (range) of preoperative FT3 and FT4 were 3.68 (3.24-4.47) and 15.48 (14.47-17.97) pmol/L, respectively. The median of TSH was 1.09 (0.24-4.79) mIU/L. FT3 levels were below normal value (< 3.34 pmol/L) in 24%, 64.5%, and 8% of the patients preoperatively, postoperatively and 3-months after the shunting, respectively (p < 0.001). When comparing preoperative and postoperative thyroid hormone profiles, significant decrease occurred in FT3 and TSH, while FT4 increased significantly (all p < 0.001). 3-months after the shunting thyroid hormones restored to the normal range. Preoperative higher FT3/FT4 ratio related to a poor 3-months outcome in depression (PHQ-9) and anxiety (GAD-7). The reported 3-months positive outcome rate in terms of depression and anxiety was 75%. Conclusion: Our study demonstrated that some deficiencies of hypothalamic-pituitary-thyroid axis may improve at 3-months after the ventriculoperitoneal shunting among patients with iNPH. Increased preoperative FT3/FT4 ratio was associated with reduced quality of life.
Introduction: NPH is a progressively incapacitating illness that when treated can have an important impact on patients´ quality of life and independence. This improvement is bound to NPH´s reversible nature. In general, along with clinical improvement comes a diminishing of caregiver burden, nevertheless, in our experience, caregivers may be faced with new and more demanding challenges as a consequence of clinical improvement which brings a paradoxical increase in their burden. Methods: We made a case series study. Patients with NPH diagnosis who underwent shunt placement surgery during 2017-2022, had clinical overall improvement of NPH symptoms and had a notable increase in their Zarit Burden Interview were included (n = 7). Each case was analyzed individually in order to identify the devolpment of symptoms after surgery as well as the caregiver´s burden. Results: The patients analyzed had an improvement of at least 2 of the symptoms of the NPH triad and their caregivers experienced an increase of at least 5 points in Zarit Burden Interview. On average caregivers had a 10.7 points of increase. Caregivers report that the clinical improvement of the patients increased the risk of falling, and added. Conclusions: Contrary to what is expected when positively impacting an incapacitating illness such as NPH, the caregiver burden may increase in caregivers of patients with NPH after shunt placement. The improvement of gait and cognitive impairment might worsen and/or develop new needs for patients and, as a consequence, add to the car-egivers´ responsibilities.
Introduction: Mini mental state examination (MMSE) or Montreal cognitive assessment (MoCA) tests are commonly used for screening of cognitive function. A battery of neuropshycological tests, designated for iNPH, can be used for more extensive evaluation (Hellström scale). In this study we aimed to compare MoCA and MMSE, and their agreement with the Hellström scale for assessment of cognitive function in patients with iNPH. Methods: Patients under evaluation at the iNPH clinic in Uppsala during autumn 2020 were invited to participate. They performed the different cognitive tests during the same day. The occupational therapist performed Hellström and MMSE-tests, whereas the MoCA tests were conducted by two physicians. The interrater agreement was calculated. Results: Fifty-four patients completed all tests. The total median score was lower on MoCA (23, IQR 6.25) than MMSE (26.5, IQR 6)(p < 0.001). Further, the patients achieved lower scores on MoCAs short term memory test and figure copy test, compared to the corresponding tests in MMSE (p < 0.001). A higher correlation to the neuropsychology part of the Hellström scale was found for the results of MoCA compared to MMSE (r s = 0.833 vs r s = 0.685). The intraclass correlation coefficient between raters was 0.995 (95% CI 0.976-0.999) for MMSE and 0.953 (95% CI 0.532-0.997) for MoCA.

Conclusions:
The results of the neuropsychology domain of the Hellström iNPH scale correlated stronger to MoCA than to MMSE. In everyday clinical practice, an uncomplicated and timesaving test like MoCA could be an alternative in the assessment of cognitive impairment in iNPH.

Introduction:
The incidence of iNPH has mainly been estimated from clinical materials. One previous study from Japan calculated the annual incidence of iNPH among 70-years-olds to 1.2 /1000 persons (Iseki et al. 2014). In this prospective cohort study, we aimed to estimate the annual incidence of iNPH among Swedish inhabitants aged 65 years and older. Methods: This study is part of a population-based prevalence study carried out 2014-2015, previously described by our group. A subgroup of 168 participants aged over 65 years, who had completed both imaging and neurological examination were re-invited for a two-year follow-up. Out of them, 122 underwent repeated examinations. Symptom assessment was made according to the NPH scale by Hellström (Hellstrom et al. 2012) and radiological evaluation according to iNPH Fluids Barriers CNS (2022) 19:104 Radscale (Kockum et al. 2018. The study participants were categorized according to the Japanese diagnostic guidelines 2nd edition. Results: At baseline 130 participants were diagnosed as unlikely, 28 as possible, and 10 as probable iNPH. At follow-up ten participants had changed their diagnosis from unlikely to possible iNPH, corresponding to a cumulative incidence of 38.5/1000 persons over 1 year. In addition, one with possible iNPH changed to probable iNPH at follow-up. Those with probable iNPH remained in the same diagnostic category. Conclusions: In this prospective study of a sample of individuals over 65 years old, the annual incidence of (possible) iNPH was 38.5/1000 person-years which is higher than previously described but in line with reports of a rapidly increasing prevalence with age.
The impact of telesensors on neurosurgical service demand: a cohort cost-effectiveness analysis from institutional and patient perspectives Ptolemy D.  (1) Introduction: Implantable telemetric intracranial pressure sensors (telesensors) enable routine, non-invasive ICP feedback which can assist with clinical decision-making and attribution of pressure-related symptoms in patients with CSF shunt systems. Here, we aim to characterise telesensor cost-effectiveness and impact on service demand. Methods: A single-centre, retrospective, cohort study and costeffectiveness analysis of 80 patients (78% Female; 30% IIH, 22% Chiari malformation, 48% other) with MScio ® (Christoph Miethke) telemetric ICP monitors. Service demand in the two years before and after implantation were retrieved from the centre's electronic patient record system. Intentionally, data did not overlap with the COVID-19 pandemic period. The frequencies of hydrocephalusrelated neurosurgical admissions, outpatient clinics, and scans were recorded along with A&E, neurology, and ophthalmology encounters. Tariffs were used to compare expenditure before and after implantation. Results: Significant reductions were seen in the frequencies of neurosurgical admissions (1.9/year to 0.6; p < 0.001), ICP monitoring (0.4 to 0.01; p < 0.001), and CT scans (0.5 to 0.3; p = 0.013) following implantation. There were also significant reductions in the proportion of patients requiring admissions (91% to 45%; p < 0.001) and ICP monitoring (30% to 3%; p < 0.001). There were non-significant reductions in other invasive procedures, neurology encounters, and A&E admissions. Overall, there was a £341 (SD = 1069) per patient per year saving (22% reduction in included costs). Conclusions: From an institutional perspective, the implantation of telesensors contributes to a reduction in service demand and a net financial saving. From a patient perspective, fewer appointments, invasive procedures, and radiation exposures suggest an improvement in patient experience and safety.
Introduction: NPH is a challenging diagnosis since after 70 + years of its first scientific description there is still controversy regarding the standard indications for surgery. In our center we believe that a timely and justified diagnosis brings about positive outcomes. In order to improve the odds of the patient we offer a standardized, interdisciplinary evaluation prior and after lumbar puncture, as well as a yearlong follow-up after surgery. This paper aims to show the clinical outcomes of patients that undergo the protocol of the Center for Clinical care of NPH at FSFB. Methods: We made a retrospective cohort-study. We included patients who underwent shunt placement surgery from 2018 to 2022 and attended to their 1 month follow-up (n = 36). We measured each symptom of the clinical triad individually and determined a positive overall outcome when patients improved in at least 2 of the 3 symptoms, or 1 of the 2 symptoms when they did not experience urinary incontinence. Results: We found that 75% of patients improve their gait, 78.7% of patients improve their urinary incontinence, 80.5% improve in at least 1 and 66% improve in both of our cognitive tests. 86.1% of patients had a positive overall outcome and 58.33% of patients improve in all of the symptoms of NPH. Conclusions: We consider that our positive results ratify the importance of a global approach to the diagnostic process of NPH. When properly evaluating the performance of patients we improve our chances of positively and notably impacting our patients' quality of life.
Introduction: Managing patients with hydrocephalus requires repeated cross-sectional imaging. In adults, this is typically CT or less commonly MRI. However, CT poses cumulative radiation risks and MRI is costly. Ultrasound is a radiation-free, relatively inexpensive, and optionally point-of-care alternative, but is prohibited by limited windows through an intact skull. We describe our initial experience with transcutaneous transcranial ultrasound through sonolucent burr hole covers in post-operative CSF disorder patients. Methods: Using cohort study design, infection and revision rates were compared between patients who underwent sonolucent burr hole cover placement during new ventriculoperitoneal (VP) shunt placement and endoscopic third ventriculostomy (ETV) over a one-year study time period and controls from the period one-year prior. Post-operatively, trans-burr hole ultrasound was performed in the clinic, at bedside inpatient, and in the radiology suite to assess ventricular anatomy. Results: Satisfactory coronal ultrasound images of the ventricles were collected for all patients. Thirty-seven sonolucent burr hole cover patients were compared to 57 historical control patients. There was no statistically significant difference in infection rates between the sonolucent burr hole cover group (1/37, 2.7%) and the control group (0/57, p = 0.394). Revision rates were 13.5% versus 15.8% (p = 1.000), but no revisions were related to the burr hole or cranial hardware. Conclusions: Trans-burr hole ultrasound is feasible for gross evaluation of ventricular caliber post-operatively in patients with sonolucent burr hole covers. There was no increase in infection or revision rate. This imaging technique may serve as an alternative to CT and MRI in the management of select hydrocephalus patients.
Introduction: Pathophysiology of Type I Chiari malformation (CMI) is not well understood but known to be a cerebrospinal fluid (CSF) related disorder. As CSF circulates with the cardiac cycle, pressure gradients between the CSF and cerebral blood flow (CBF) induce central nervous system (CNS) tissue motion which can result in tissue stretching and compression. We hypothesized that CNS tissue motion measurements would be abnormal in CMI patients and normalize after posterior fossa decompressive surgery. Methods: Tissue motion in the rostral-caudal direction in three regions of interest were quantified with two-dimensional phase-contrast magnetic resonance imaging (2D PC-MRI) in nine CMI patients, before and after surgery, and compared with those in 10 healthy volunteers. Peakto-peak differential displacement was quantified as the displacement of either the cerebellar tonsil or the pontomedullary junction relative to the upper spinal cord. A linear mixed effects model determined significance at the 0.05 level. Results: We found significant differences (p < 0.05) between Chiari patients and controls in displacement of the spinal cord (Chiari: 0.51 ± 0.2 mm, Control: 0.72 ± 0.29 mm) and tonsil (Chiari: 0.25 ± 0.15 mm, Control: 0.14 ± 0.05 mm), but not within the pons (Chiari: 0.17 ± 0.07 mm, Control: 0.19 ± 0.03 mm). We did not see significant differences in displacement between Chiari patients pre-and post-operatively. Conclusions: These results show cardiac-induced neural tissue motion in the rostral-caudal direction is altered in the CMI disease state compared to healthy controls however, this tissue motion was not normalized after surgery.  (1) Introduction: Most hydrocephalus is the communicating type, with the common etiology thought to be obstruction of CSF flow at the level of the arachnoid granulations (AGs). When treated with a shunting device, treatment failure mechanisms are often catheter related. The proposed project aims to address the failure mechanisms by developing a catheter-free completely passive miniaturized valve. The valve restores normal CSF drainage by bypassing defective AGs. By implanting the valve in the venous sinus/dura tissue, the need for persistent intracranial penetration via catheters is fully eliminated. Methods: This self-seal valve is composed of two membranes fabricated by a 3D printer (Form 3 + , Formlabs). In its closed state the top membrane seals the perforations on the bottom membrane. The top membrane deflects upward to expose a conduit for fluid flow in the open state when ICP is higher than valve opening pressure. The valves are measured in a bench-top model to show its ideal hydraulic property for the treatment of hydrocephalus. Results: The basic flow response of the valve was measured in our CSF fluidic circulatory setup. The valve showed a highly directional hydrostatic response with little reverse flow leakage. The reverse flow leakage was negligible, at approximately 1.0 µl/min on average. The valve opening pressure, P T , was approximately 50 mmH 2 O. Conclusions: The proposed valve is fabricated by 3D printing technology and demonstrated the target hydrostatic characteristics for CSF drainage mechanisms, based on measurements on the bench-top model. This valve has three favorable design specifications: non-zero valve-opening pressure, negligible clogging and reverse flow leakage, and simplicity in design and fabrication process.  (1) introduction: Outcome of CSF diversion in Normal Pressure Hydrocephalus (NPH) patients is time-dependent; with earlier treatment associated with better outcomes. In this ongoing study, we aim to analyse the time period of various stages of NPH assessment and investigation from first referral to neurosurgery services, to shunt placement. Methods: Retrospective review of electronic health records was performed for consecutive patients undergoing ventriculoperitoneal (VP) shunting for NPH over two consecutive months (February-April 2022). Demographic and clinical information was collected alongside dates of: referral sent to neurosurgery, referral received by neurosurgery, first outpatient review, and dates of interventions. Time interval between each consecutive step of our service provision was calculated to identify key time-limiting steps. Results: Fifteen patients (mean age 75.6 (± 3.8) years) were identified, all undergoing insertion of a VP shunt. Mean lead time between sending of referral and VP shunting was 321(± 104) days. Of this, 17(± 16) days elapsed between referral sending and receipt, followed by 62(± 22) days until clinic review, and a further 229(± 75) days until shunt surgery. Patients undergoing extended lumbar drainage (LD) protocol waited 249 days from referral to shunting versus 188 days for those who proceeded directly to shunt (p = 0.62). Conclusions: In this ongoing service evaluation, we established the mean waiting time from referral to shunt placement, identifying the longest lead time in the patient journey as between outpatient clinic and shunt placement. Since clinical improvement is time-dependent, we hope this study will help guide workflow optimisation in neurosurgical units to improve patient outcome following shunting.  (1) Introduction: The timed 10 m walking test is a frequently used assessment in normal pressure hydrocephalus (NPH) and decompensated long-standing overt ventriculomegaly (LOVA). We aimed to make a smart-phone app which performs the timed walking test and records the results for individual patients, thus making it possible for patients with a suitable smart phone to perform repeat assessments. Methods: The iPhone built-in accelerometer was used to generate events for the app through CMMotionManager class. The non-purchase app is set at default 10 m, but the walking distance can be manually changed. When distance is set, the app gives verbal countdown notice of 3 s before it verbally instructs to 'start walking' . When the preset distance is covered in a straight line, the app verbally informs the patient to 'stop' , and displays the result in measure of distance covered, time taken to cover set distance and number of steps taken. This result can be saved and compared with future results. Results: The app was validated in 50 subjects with timed slow-pace and fast-pace 10 m walking test. Compared to a clinical observer using a stopwatch, the app showed 100% accuracy in the measure of time taken to cover distance, 95% accuracy in the number of steps taken with an error ± 1-3 steps, and 97% accuracy in the measure of total distance covered with error of ± 0.25-0.50 m. Conclusion: This is an efficient app for objective performance of timed walking test in NPH and LOVA patients.

What are the barriers to delivering timely CSF diversion in patients with NPH? Results of a single-centre service evaluation
Introduction: Laparoscopic insertion of the distal tube of ventriculoperitoneal shunts is associated with lower incidence of catheter migration and malposition, compared to mini laparotomy 1 . We present a single-centre study on peritoneal catheter insertion following implementation of guidelines for VP shunt insertion, which among others promoted laparoscopic insertion, especially in the presence of obesity. Methods: A retrospective analysis of shunt operations between May 2020 and August 2021 was performed to assess the impact of the surgical technique of the peritoneal catheter insertion on revision rates. Collected data included: primary or revision surgery, indication for shunting, surgical approach, previous and subsequent revisions, and patient demographics including body mass index (BMI). The revision rate of shunts inserted laparoscopically was compared to those inserted via a mini laparotomy. Results: One hundred twenty nine patients underwent shunt insertion during the study period, out of which 16.3% of cases were performed laparoscopically. Laparoscopic insertion was associated with significantly lower revision rates compared to insertion via a mini-laparotomy (4.7 vs. 19.4%, p < 0.001). Mechanical failure was the primary indication for overall shunt revision. Patients with catheter migration and malposition had a higher BMI (37.08 vs. 30.67, p < 0.001).

Conclusions:
The use of laparoscopy in ventriculoperitoneal shunt insertion was low in our series, but it was clearly associated with lower shunt revision rates. Patients with high BMI particularly benefit from laparoscopic insertion. Streamlining the surgical pathway for laparoscopic insertion of shunts is expected to lead to better surgical outcomes.  Introduction: Hydrocephalus often involves failure of cerebrospinal fluid (CSF) circulation which can be accompanied by a cerebral blood flow (CBF) deficit. The nature of coupling between CSF circulation and CBF is poorly described, given that investigations require invasive monitoring of intracranial pressure and CBF. We sought to explore which components of CSF pressure-volume compensation correlate with global CBF. Method: 36 adults diagnosed with hydrocephalus underwent an infusion test to assess CSF compensation, including measurement of baseline CSF pressure, pulse amplitude of CSF pressure (AMP), resistance to CSF outflow (Rout), cerebrospinal elasticity, the magnitude of slow vasogenic CSFp waves. Global CBF was estimated using a formula including Transcranial Doppler Ultrasonography flow velocity measurements, the slope of the regression line between AMP and CSF pressure from the period of CSF infusion and elasticity. Results: Univariate analysis indicated a significant negative correlation between Rout and CBF (R = − 0.37; p = 0.035). Higher Rout (> 15 mmHg/(ml/min)) was observed when CBF was low (< 400 ml/ min). There was also a significant correlation between CBF and the magnitude of slow vasogenic waves of CSFp at baseline (R = − 0.43; p = 0.013). Conclusion: It is not known if the disturbance in CSF circulation causes a decrease in CBF or vice versa. Also, a decrease in the magnitude of slow vasogenic waves is associated with lower CBF. In traumatic brain injury, a low magnitude of slow ICP vasogenic waves is associated with poor outcome. In hydrocephalus, we do not see such an obvious link. Study supported by: Revert Project, Interreg, France (Channel Manche) England, funded by ERDF.  (1) Introduction: Tap test improves symptoms of idiopathic normal pressure hydrocephalus (iNPH); hence, it is widely used as a diagnostic procedure. However, it has a low sensitivity and there is no consensus on the parameters that should be used nor the volume to be extracted. We propose draining cerebrospinal fluid (CSF) during tap test until a closing pressure of 0 cm H2O is reached as a standard practice. We use this method with all our patients at our clinic. Methods: This is a descriptive cross-sectional study where all patients with presumptive diagnosis of iNPH from January 2014 to December 2019 were included in the study. We used a univariate descriptive analysis and stratified analysis to compare the opening pressure and the volume of CSF extracted during the lumbar puncture, between patients in whom a diagnosis of iNPH was confirmed and those in which it was discarded. Results: A total of 92 patients were included in the study. The mean age at the time of presentation was 79.4 years and 63 patients were male. The diagnosis of iNPH was confirmed in 73.9% patients. The mean opening pressure was 14.4 cm H2O mean volume of CSF extracted was 43.4 mL. Conclusions: CSF extraction guided by a closing pressure of 0 cm H2O instead of tap test with a fixed volume of CSF alone may be an effective method of optimizing iNPH symptomatic improvement and diagnosis.

Introduction:
The aim of the present study was to investigate vascular and morphological choroidal features in patients with idiopathic Normal Pressure Hydrocephalus (iNPH), before and after shunt surgery, compared to a control group. Methods: The Bologna PRO-Hydro multidisciplinary team prospectively recruited 12 consecutive patients diagnosed with iNPH between November 2021 and March 2022 with indication for ventriculoperitoneal (VP) shunt surgery. An ophthalmic evaluation was conducted at the IRCCS Department of Ophthalmology at Hospital Sant'Orsola before and after a mean of 47.6 days (SD = 6.97) from shunting. Spectral-domain optical coherence tomography (SD-OCT) with enhanced depth imaging (EDI) was conducted. Images were binarized using the ImageJ software. Parameters studied were total choroidal area (TCA), luminal choroidal area (LCA), choroidal stromal area (SCA), sub-foveal choroidal thickness (SFT) and retinal nerve fiber layer (RNFL) thickness. Choroidal vascular index (CVI) was calculated as the ratio between LCA and TCA. Results were compared with 12 healthy, age-matched controls. Results: SCA and SFT were significantly increased in iNPH patients after surgery compared to control group (1.2846 vs 0.975 mm 2 , 305 vs 204.5 mm, p = 0.031 and p = 0.019 respectively). CVI in iNPH patients was reduced compared to control group (62.73 vs 66.49%, respectively), though the difference was not statistically significant (p = 0.092). Conclusions: iNPH patients treated with VP shunt showed an increased SCA and an increased SFT compared to control group. These results support the hypothesis that VP shunt surgery may determine hemodynamic and morphological alterations of the choroid in patients with iNPH.  (1) Introduction: Aqueduct stenosis is considered congenital and acquired, but not well understood because it is a rare disease. Stenosis is often well tolerated for several years, but is not constant and is aggravated by meningitis, hemorrhage, or trauma and the like. Case presentation: A 17-year-old male presented with severe headache. The headache was so severe that it interfered with his daily life. Magnetic resonance imaging (MRI) showed mild ventricular enlargement above the aqueduct. In addition, stenosis of the aqueduct was observed due to a thin septum. With no other cause of headache and the fact that the ventricles were enlarged for his age, we performed Endoscopic third ventriculostomy(ETV) and aqueductoplasty. Operation was performed under the general anesthesia. At first, The aqueduct stenosis was made up of several thin septal walls and performed aqueduct septostomy with fogarty balloon. Next, ETV was performed. The ventricles size was quickly decreased, and the headache improved after the surgery. Discussion: When ventricular enlargement is mild as in this case, endoscopic manipulation is difficult due to the lack of structural dilatation; septostomy should be performed first because ETV first will further shrink the ventricles and make manipulation more difficult. Aqueduct stenosis is rare and is often detected in chronic hydrocephalus and cognitive decline. The present case was extremely rare case of early detection by headache. The optimal timing of treatment is Introduction: Today, magnetic resonance imaging (MRI) work-up of idiopathic normal pressure hydrocephalus (iNPH) is largely focused on anatomical derangements of cerebrospinal fluid (CSF) spaces. We introduced a MRI biomarker of CSF disturbance in iNPH, based on grading of ventricular reflux of an intrathecally administered MRI contrast agent (gadobutrol; 0.25 or 0.5 ml, 1 mmol/ml), serving as a CSF tracer. In ventricular reflux grades 3 and 4, CSF tracer remains in ventricles at 24 h after injection. Methods: In iNPH patients, the functional imaging biomarker Ventricular Reflux Grade was compared with anatomical MRI biomarkers of CSF space anatomy (Evans' index, callosal angle and disproportional enlargement of subarachnoid spaces hydrocephalus), imaging biomarkers of neurodegeneration (Schelten's medial temporal atrophy scores, Fazeka's scores and entorhinal cortex thickness), intracranial pressure (ICP) scores indicative of intracranial compliance, as well as clinical response to shunt surgery. Results: Ventricular reflux grades 3-4 were related to findings of abnormal pulsatile ICP, indicative of impaired intracranial compliance, and also were frequent in shunt-responsive iNPH. Conclusions: Grading of ventricular reflux of CSF tracer may add information to traditional imaging scores of CSF space anatomy by providing a functional measure of CSF disturbance in iNPH.  (1) Introduction: Ventricular catheters stimulate reactive neurological cells and tissues responsible for many shunt obstructions through mechanical, fluidic, and material stimuli. A multi-objective design framework is proposed for evaluating ventricular catheters. Methods: Literature on ventricular catheter obstruction, ventricular anatomy, circadian rhythms of cerebrospinal fluid production, neuroglial cells' fluid shear response, catheter placement forces, and optimization of catheter fluid dynamics were reviewed to establish design objectives. A standard ventricular catheter, a flow-balanced catheter, and an example novel design with elongated fenestrations were evaluated against these objectives. Three-dimensional computational fluid dynamics simulations quantified volumetric flow and fluid shear distributions. Results: The design framework objectives for an ideal ventricular catheter are: (1) minimize parenchymal inflammatory response by minimizing catheter diameter; (2) maximize the distance between fenestrations and surrounding tissue; (3) maintain fluid shear below the critical shear for astrocyte IL-6 upregulation across CSF production rates; (4) maximize the distance cells must bridge when occluding fenestrations; (5) select a bio-inert catheter material; (6) withstand catheter insertion forces; and (7) be manufacturable on a commercial scale. As with many multi-objective problems, the conflicts inherent in this framework constrain the design space for improved ventricular catheters. The design with elongated fenestrations improved criteria 1,2,3,4 compared to the standard design, and criteria 3,4,7 compared to the flow-balanced design. For criteria 3, the elongated fenestrations reduced both maximum fluid shear and surface area experiencing critical shear compared to both standard and flow-balanced designs. Conclusions: Future applications of this multi-objective catheter design framework may help reduce ventricular catheter obstruction.  (1) Introduction: Idiopathic normal pressure hydrocephalus (iNPH) can be considered a treatable dementia since shunt therapy is effiient in improving symptoms. The long-term results of the cerebral spinal fluid (CSF) shunt have shown variable results without offering firm conclusions. Here we present the results of a retrospective study investigating the long-term results of iNPH patients treated with ventriculoperitoneal shunt (VPS) using programmable valves. Methods: The symptoms before treatment were recorded. Post-VPS clinical symptoms and outcomes were assessed based on changes in gait, urinary incontinence, and cognitive dysfunction in a yearly follow-up spanning at least 10 years. Results: Among a total of 65 patients treated. The median age was 71 years, and the mean follow-up time of the surviving patients was 140.5 ± 1.6 days. Overall, there was a significant and persistent improvement among all symptoms compared to the baseline (p < 0.05). Gait was the symptom with better and sustained improvement when compared with the baseline (p < 0.05). Mental impairment and urinary incontinence improved in the early follow-up (p < 0.05) followed by a reduction in the later follow-up. Twelve patients (18.4%) required surgical revisions for shunt malfunction. Change in valve pressure was performed in 35 patients (54%). Overall, 95% of revisions resulted in clinical improvement. Conclusions: This study expands our previous results showing that surgical treatment for iNPH by VPS is still a safe modality that improves symptoms in most affected patients, even in the long term.

Multi-objective framework for ventricular shunt catheter design
Introduction: Ventriculoperitoneal shunt (VPS) is the commonest surgery performed by paediatric neurosurgeons. Despite the progress made, shunt failures remain a significant issue. We aim to develop a NNI paediatric VPS (NNI-pVPS) prognostication model to predict shunt failures in hydrocephalus. Methods: A retrospective review of 214 paediatric VPS was performed. Patients with complex hydrocephalus (multiloculated or > 1 ventricular catheter required) were excluded. Patient characteristics, hydrocephalus and shunt details, and outcomes were documented. Non-technical failure included infection, occlusion or other causes not related to malposition or incorrect assembly. Results: Mean age at VPS insertion was 6 months with a mean follow up duration of 44 months. The commonest type of hydrocephalus was obstructive (n = 142, 66.4%) and the commonest etiology was tumour related (n = 66, 30.8%). Most shunts were primary insertions (n = 131, 61.2%) and valves used were mostly non-programmable (n = 182, 85.0%). The 30-day non-technical shunt failure rate was 9.3%; 9 infections (4.2%), 7 occlusions (3.3%), and 4 others (1.9%). The NNI-pVPS Introduction: Isolated fourth ventricle is a rare complication in hydrocephalus patients. Different treatment strategies have been proposed for its management, like endoscopic aqueductoplasty or IV ventricleshunting. However, the loculation of the IV ventricle can make the control of this entity difficult. Methods: We present a case report of a biloculated and isolated fourth ventricle patient. We present the treatment strategies we performed to control this arduous pathology. Results: A seven-year-old female patient affected by posthemorrhagic hydrocephalus and an isolated fourth ventricle that went through a failed endoscopic aqueductoplasty with a stent. Because of repeated isolation events and neurological deterioration with an increased size of the isolated IV-ventricle, she required IV-ventricle shunting. During the follow-up, the IV ventricle developed intraventricular septae, which loculated this cavity, causing progressive neurological impairment. Our first strategy was to perform open surgery to reconnect the two loculations of this isolated IV ventricle. Even though these septae were successfully opened on two occasions, the patient continued to develop new septae a few weeks after these open procedures. Because of this recurrent loculation, we decided to open both cavities and connect them to a single IV-ventricle shunt using a Y connector. After this final surgery, we managed to control this rare entity and loculations did not increase their size again. Conclusions: Loculated and isolated fourth ventricle is a rare complication with very difficult management. We present a case that only improved after multiple surgeries and a final debridation and connection of both loculations to the same device. Consent to publish had been obtained.  (1) Introduction: Congenital hydrocephalus is one of the most common causes of neurosurgical consults globally. Management delays may cause unique complications such as spontaneous cutaneous rupture and cerebrospinal fluid leakage. This may occur frequently in low-tomiddle income countries, where prenatal and neurosurgical healthcare services are less accessible; however, no such cases have been recorded in the Philippines. Methods: We present two cases of severe hydrocephalus with spontaneous cutaneous rupture previously seen at our institution. Results: The first case is a 7-month-old female with leaking CSF from a 1-cm spontaneous cutaneous rupture at the right anterior aspect of her anterior fontanelle. On admission, her head circumference was 85 cm. Her imaging showed markedly dilated lateral ventricles with pneumoventricle, and a widened anterior fontanelle. Her defect was sutured and she was treated with appropriate antibiotics. She was discharged once infection resolved but eventually expired at home. The second is a 3-year-old male who presented with leaking CSF from a cutaneous rupture at the anterior border of the posterior fontanelle. His head circumference was 92 cm, with a 4-cm scalp defect exposing the underlying ventricle. The defect was sutured at the emergency room. His family refused further diagnostics and treatment, and opted to bring him home, and was lost to follow-up. Conclusions: Only a few case reports on spontaneous cutaneous rupture are available to guide its treatment, with none coming from the Philippines. Our cases establish the local incidence of this underreported complication and demonstrate that simple suturing and antibiotic treatment do not lead to desirable outcomes. Consent to publish had been obtained. Fluids Barriers CNS (2022) 19:104 report our institution's experience and serve as ground for future improvement. Methods: This is a single centre retrospective case series study. Data regarding current age, hydrocephalus etiology, number of shunt revisions in childhood and after transition, type of presentation (acute vs routine follow up), type of valve, length of follow up was collected. Results: A total of 227 patients were included (mean 32 years, min 16max 68 years; SD ± 11.9). 122 were transitioned from the nearest paediatric center, Great Ormond Street Hospital; 105 from other national and international hospitals. Common hydrocephalus etiologies were: post haemorrhagic 19.8%, Chiari II 12.7%, Aqueduct stenosis 12.7%, congenital 8.81%, post infectious 7% and tumor 5.2%. Hydrocephalus following hemisperectomy, associated with syndromic craniosynostosis or idiopathic intracranial hypertension was rare. In 16.7% (38 cases) no cause could be identified, despite review of available crosssectional imaging, due to insufficient documentation. 171 (75.3%) patients were seen electively, 37 (16.2%) presented with suspicion of acute shunt dysfunction and 19 (8.3%) were referred by other specialists after the patients were lost to follow up. Patients presenting acutely were more likely to come from other centers 28/105 (26.7%) compared to 9/122 (7.37%) from Great Ormond Street Hospital (p < 0.005; Wilcoxon Signed Rank). 66/227 (29%) patients underwent at least a CSF diversion intervention in adulthood. Conclusion: Hydrocephalus is a condition that requires lifelong neurosurgical follow up. A more structural approach towards transition is needed. Funding and disclosures: The authors did not receive any funding for the completion of this work. The authors report no conflicts of interest Fluids Barriers CNS (2022)  Results: Eighteen studies were eligible for our systematic review. Although many biomarkers have been investigated for differential diagnosis of iNPH, amyloid-b 42 (Ab42), total-tau (t-tau), and phosphorylated tau (p-tau) are the most efficient candidate markers to discriminate iNPH from AD patients. Additional biomarkers categorized Fluids Barriers CNS (2022) 19:104 transcutaneous flow (TTF) is a noninvasive tool to evaluate cerebrospinal fluid (CSF) flow in VPS. The diagnostic accuracy of TTF to detect shunt patency was assessed. Methods: All consecutive patients with communicating hydrocephalus and VPS who initially demonstrated improved gait velocity followed by decline at a single center were eligible for inclusion and underwent TTF tests in the sitting position before and after SPS (reference standard). Results: As of April 2022, 8 patients met eligibility and demonstrated patency by SPS. TTF confirmed flow in 6 of the 8 patients resulting in a specificity of 75% and negative predictive value of 100%. Conclusions: Preliminary results show that TTF may be a helpful noninvasive tool to screen patients prior to consideration for invasive studies to evaluate VPS patency. The final result after complete accrual is awaited.

Spontaneous
Introduction: Intracranial pressure (ICP) typically requires invasive monitoring for accurate measurement. The utility of non-invasive MRI biomarkers, including enlarged optic nerve sheath (ONS) diameter and hypophysis compression are unclear, and likely to be inaccurate when viewed in 2-dimensions. We aimed to evaluate 3-dimensional MRI-based segmentations of the ONS and hypophysis as objective markers, assessing their relationship with 24-h ICP readings. Methods: A single-centre retrospective study included patients who underwent high-resolution isotropic T2w MRI within three months of 24-h ICP monitoring. Semi-automated segmentations of the ONS and hypophysis were performed with inter-subject intracranial volume normalisation. Volumetric measurements were correlated with CSF pressures. Results: 25 patients (mean age: 44-years, females: 14) were included. 20 patients had raised ICP in the sample, of these 14 underwent CSF diversion procedures. Left ONS and hypophysis volume were both significantly correlated with 24-h ICP readings (Pearson correlation coefficients: 0.45 and 0.60, p = 0.049 and 0.02). Mean values of left ONS volume (752 ± 222 mm 3 ) were significantly higher in patients with raised ICP versus normal (523 ± 177 mm 3 ), (p = 0.04) and higher left ONS volume was significantly associated with patients undergoing CSF diversion (p = 0.02). No significant difference was found between right ONS volume and raised or normal ICP patients, however, right ONS volume was significantly associated with left ONS volume and future CSF diversion (p = 0.05). Conclusions: MR-based volumetric segmentations, including unilateral ONS enlargement, are significantly associated with raised ICP and the need for intervention. Further work seeks to expand on this sample and compare against other non-invasive imaging biomarkers.
Introduction: Despite the prevalence of shunt obstruction and the high rate of shunt revisions, there are a limited number of methods that improve our understanding of the overall degree of obstruction without exhaustive, high-end histological analysis. Methods: The current study develops an inexpensive, easy to use gravity-driven model that measures flow through naïve and explanted ventricular catheters from patients. The purpose of this model is to provide a quick, simple analysis of the resistance to CSF flow through the ventricular catheter caused by tissue obstruction. Catheters of several manufacturers were tested. Flow and pressure data were measured using appropriate sensors; resistance to outflow of different catheter designs were evaluated. A subset of experiments measured changes in relative resistance when catheter hole interfaces were progressively and systematically blocked. Relative resistance of explanted catheters from our clinical shunt biobank was also measured. Results: The model was built and tested that provides data on overall obstruction of ventricular catheters, of which can be sent wirelessly to researchers worldwide when appropriate. Experimental results from our gross analysis of resistance showed that there are significant differences between the relative resistances of different catheter models without obstruction at all. In samples explanted from patients, we see varying degrees of resistance to CSF flow through the system, indicating the potential for our testbed to quantitatively differentiate bulk tissue obstruction with high throughput.

Conclusions:
The current study is intended both to validate the proposed model and to examine data on differences in relative resistance between catheter models.  (1) Introduction: Current in-vitro models for cellular adhesions in shunts have limited scalability due to model complexities. An assay capable of large concurrent sample sizes is proposed for assessing materialmediated neuroglial cellular adhesion to shunt catheter materials. Methods: Astrocyte adhesion to three Shore 50A platinum cured silicone tubes (A, B and C) were evaluated. The assay consists of 5 mm long tubes with transverse fenestrations in 1 mL of media in conical vials. Each sample is seeded with 250,000 astrocytes/ml and incubated on an orbital shaker with continuous agitation to provide fluidic shear to stimulate astrocyte adhesion. The assay can accommodate up to 30 samples concurrently and run for multiple weeks. For comparison, astrocyte adhesion to the same materials were also evaluated via bioreactors with recirculating media at a more physiologically relevant flowrate of 20 ml/hr. All samples were cut in half longitudinally, fixed, stained, and imaged via fluorescent confocal microscopy to quantify percent surface coverage. Results: Initial evaluations of silicone materials A, B and C exhibited differences in percent astrocyte surface coverage even though the materials were nominally equivalent. These results agree with surface coverage trends observed in the more complex bioreactor studies. Conclusions: The assay offers an efficient, yet simple, method to assess material-mediated cellular adhesions with statistically significant samples sizes. Despite not utilizing physiologically relevant CSF dynamics, the mechanical agitation is able to stimulate neuroglial cell adhesion. This assay could serve as a screener for assessing material-mediated cellular adhesions in shunt and other neurological applications.

A high-throughput assay for screening material-mediated cellular adhesion for neurological implants
Finite state machine for position dependent hydrocephalus shunt therapy David Iselin 1 , Joris Chomarat 1 , Caroline Holzer 1 , Janina Hug 1 , Tiago Hungerland 1 , Luca Krebs 1 , Rosina Weiss 1 , Fabian Flürenbrock 2 , Leonie Korn 2 , Anthony Podgoršak 1 , Dominik Schulte 1 , Nikolaos Tachatos 1 , Markus Introduction: Patients with idiopathic intracranial hypertension (IIH) and vision threatening papilloedema require cerebrospinal fluid (CSF) diversion. We have developed a surgical protocol for CSF shunting in these patients that includes the integration of the M.scio telemetric sensor (Meithke, Potsdam, Germany). This observational study describes the intracranial pressure (ICP) characteristics of shunted patients with IIH. Methods: Sixty-two consecutive IIH patients underwent ventriculoperitoneal shunt insertion from July 2019 to February 2022 and we have available telemetric ICP recordings for 53. The first telemetric ICP recording after shunt implantation was assessed, in order to analyse the main parameters of the ICP waveform. Recordings from malfunctioning shunts were included following revision.

Results:
The ICP waveforms demonstrated arterial pulsatility in 45 (85%) patients. The lack of pulsatility did not indicate shunt malfunction in the remaining patients. In sitting position, the mean ICP was -5cmH 2 O (range -26 to 13) and the amplitude was 8cmH 2 O. In supine position, the mean ICP was 23cmH 2 O (-1 to 43) and the amplitude was 7cmH 2 O. The mean difference in ICP between sitting and supine positions was 28 cm H 2 O.

Conclusions:
The results provide a normal range of values for ICP recordings via a telemetric sensor in shunted patients with IIH. They will assist in the interpretation of ICP data in cases of shunt malfunction and may advise in the optimal valve settings. This is the first study to provide insight into the ICP characteristics in IIH patients with functioning shunts in order to inform decision making.  (1) Introduction: Although idiopathic intracranial hypertension is strongly associated with obesity, the relationship between body fat distribution and IIH has yet to be fully characterized. Pilot studies have shown that central obesity is a risk factor for IIH. This study aimed to examine parameters of body composition in IIH patients and determine if body fat distribution correlates with clinical measures of IIH. Methods: Data was collected from 360 patients seen at the Johns Hopkins Center for CSF Disorders. Body composition parameters including visceral adipose tissue (VAT), body mass index (BMI), fat mass (FM), extracellular water (ECW), and total body water (TBW) were measured using bioelectrical impedance analysis (Seca, medical Body Composition Analyzer 515; seca mBCA 515). Lumbar puncture manometry was used to measure cerebrospinal fluid opening pressure in the left lateral decubitus position. Visual acuity was assessed using LogMar charts. Color vision was assessed using HRR plates. Spearman's correlation was used to determine the correlation between opening pressure and body composition parameters.

Correlation between cerebrospinal fluid opening pressure and body fat distribution in idiopathic intracranial hypertension (IIH) patients
Introduction: Idiopathic normal pressure hydrocephalus (iNPH) is characterised by progressive disturbance of gait and postural function, affecting spatiotemporal gait parameters, kinematics and balance. To improve precision of the diagnostic work-up and optimise treatment of iNPH patients, there is a need for an objective, standardised quantification of the typical gait pattern. We explored gait function in iNPH patients in comparison with a healthy control group using an optical tracking system (OTS). Methods: INPH patients (n = 26, mean age 75.7 range 68-87, 27% females) and age-matched healthy controls (HC) (n = 22, mean age 71.6 years, range 61-82, 55% females) underwent a threedimensional gait analysis (3DGA) according to a standardized protocol using an OTS. Data of spatiotemporal and hip kinematic variables were compared across groups using non-parametric statistics. Results: All temporal gait parameters such as speed (mean 0.68 ± 0.25 (± SD) vs 1.21 ± 0.22 m/s), cadence (108 ± 15 vs 114 ± 6 steps/min), step width (0.16 ± 0.04 vs 0.09 ± 0.03 m), step length (0.79 ± 0.23 vs 1.26 ± 0.21 m) and stance (67 ± 7 vs 62 ± 3%) differed significantly between iNPH and HC groups respectively (p < 0.013). Both hip extension (-3° vs -12°) and range of hip flexion/extension (31° vs 40°) were significantly lower in iNPH patients (p < 0.001). Conclusion: 3DGA using OTS captures typical features of the iNPH gait, indicating that this method could add additional value to the routine clinical examination in the evaluation of iNPH patients preand postoperatively and be used to explore the iNPH gait pattern further.
Clinical assessment of step-height and width in iNPH using wearable sensors Tomas Bäcklund 1 , Johan Eriksson 2 , Nina Sundström 1 1 Department of Radiation Sciences, Biomedical Engineering, Umeå University, City, Umeå, 90187, Sweden; 2 Department of Clinical Science, Umeå University, Umeå, 90187, Sweden Correspondence: Tomas Bäcklund (tomas.backlund@regionvasterbotten.se) Fluids and Barriers of the CNS 2022, 19(1) Introduction: Impaired gait is a common and early symptom in patients with idiopathic normal pressure hydrocephalus (iNPH). The typical gait pattern is broad-based, shuffling and short-stepped. Clinically, gait is generally visually assessed using blunt rating scales. Wearable sensors are suggested to bridge this gap for a more precise assessment of gait in daily clinic. The aim of this study was to use an inhouse developed sensor system (Striton), to assess gait in iNPH patients before and after tap-test and shunt surgery, with an emphasis on heel-height and step-width. Methods: The Striton system was quick to attach and used to measure gait pattern during 25 m walking. Patients were assessed before and after tap-test (n = 13) or before and 3 months after shunt surgery (n = 10). Also, the gait of a group of healthy elderly (HE) (n = 83, age 70, 20 m walk) was measured. Preoperative gait parameters as well as change following tap-test/surgery were evaluated. Results: Mean heel-height and -width in the HE was 16.7 ± 0.6 cm and 5.22 ± 0.89 cm. In iNPH, after tap-test, mean heel-height at push-off was increased from 13.9 to 15.1 cm (p = 0.016), but step-width was unchanged (6.5 to 6.2 cm). The HE was significantly different from the iNPH patients (p < 0.000 and p < 0.000 respectively). However, three months after surgery, heel-height as well as step-width were improved.

Conclusions:
The measurements were easy to perform and generated objective results of parameters that are challenging to assess visually. This makes wearable sensors a promising tool for clinical assessment of gait.
Objective assessment of NPH patients following ventriculoperitoneal shunt placement using activity monitoring data Desmond A. Brown 1 , Kenton R. Kaufman 2 , Jonathan Graff-Radford 3 , David T. Jones 3,4 , Jeremy K. Cutsforth-Gregory 3 , Petrice M. Cogswell 4 , and Benjamin D. Elder 2,5 Introduction: One goal of VP shunt placement in the treatment of idiopathic normal pressure hydrocephalus (iNPH) is to improve the patient's gait. While various objective measures of gait are used in the clinic, these often provide a snapshot assessment, and there are limited data available on the real-world functional improvement following shunt placement. Methods: Nineteen patients with iNPH were fitted with 4 activity monitors (hip, thigh, bilateral ankles), worn for 4 days preoperatively and 4 days postoperatively within 30 days of surgery. Continuous measurement of steps, cadence, body position, gait entropy, and the daily proportion spent "active" or "static" were obtained. The activity monitor data were compared to the standard gait assessments, modified Rankin Score (mRS), Incontinence Score, Montreal Cognitive Assessment (MoCA) Score, and Grooved Pegboard Tests. Results: Postoperatively, there was significant improvement in mean entropy (0.60 to 0.80) and mean daily steps (2000 to 3000). There were no differences in mean cadence or percent of time spent active/static. There was no improvement noted on the mRS, MoCA, or Incontinence Score. Total steps were statistically significantly correlated with mean entropy (r = 0.742) and inversely correlated with mRS (r = − 0.501). Conclusions: Daily activity monitors provided an early objective measure of improvement in mean gait entropy and total number of steps following shunt placement in iNPH patients. There was a 50% improvement in number of steps per day in the first 30 days postoperatively, with improved gait complexity, before any improvement in measures of cognitive function. Introduction: Secondary hydrocephalus describes any CSF accumulation due to a concurrent central nervous system pathology, including subarachnoid haemorrhage (SAH) or tumour. There is little evidence on the incidence and outcomes of patients with chronic secondary hydrocephalus (defined as symptoms > 1 month in duration) undergoing a VP shunt. Methods: We conducted a single-centre retrospective cohort study on all patients undergoing a VP shunt between 06/05/2016 to 30/03/2019 Introduction: Insertion of cerebrospinal fluid (CSF) shunts is a common neurosurgical operation. In an effort to reduce revision rate, guidelines on the management of patients that require CSF diversion procedure were developed and implemented in our Department. This study evaluates the impact of the guidelines on primary shunt revision rate. Methods: A retrospective study was carried out between January 2018 and December 2020, in order to assess the change in the revision rate after the implementation of the CSF diversion guidelines in July 2019. The guidelines proposed: pathways for urgent and elective shunt operations; recommendations on peri-operative management, surgical techniques, insertion of external CSF drains and conversion to shunts; guidance in suspected malfunction; advice on clinical governance in relation to shunt surgery. We compared revision rates before and after the guidelines. Results: There were 308 patients that underwent insertion of a primary shunt during the study period, 171 before and 137 after the introduction of the guidelines. The revision rate within 6 months of the implantation procedure was 17.2% for the whole cohort, 21.6% before and 11.2% after the guidelines. This represented a significant reduction of the revision rate of primary shunts (p = 0.021). Conclusions: The introduction of local guidelines for insertion of CSF shunts significantly reduced primary shunt revision rates. We recommend development of robust surgical pathways and a reduction of variation in practice to improve outcomes for CSF shunting. Continuous monitoring of revision rates may identify modifiable factors and may further enhance shunt survival. Fluids Barriers CNS (2022) 19:104 AVIM and treatment, and AβO 10−20 ratio(AβO 10−20 at AVIM/AβO 10−20 at treatment). Results: The median [IQR] of TI was 17. 5 [13.25-29.25] months. AβO 10−20 was significantly increased at the point of treatment (p < 0.001). There was no correlation between TI and AβO 10−20 ratio(p = 0.969). Z-EI was significantly increased, and CA was significantly decreased at the point of treatment while EI showed no significant change (p = 0.020, 0.040 and 0.173 respectively). The values of AβO 10−20 significantly correlated with CA (p = 0.040). Conclusions: We determined that Aβ aggregation, vertical expansion of lateral ventricles and disproportionate enlargement of SAS along with progression of CSF stagnation. Disproportionate enlargement of SAS was considered to correlate more with CSF stagnation than ventricular expansion.

Incidence and outcomes of patients with chronic secondary
The effect of ventriculo-atrial shunt for the iNPH patients with high phosphorylated tau protein in cerebrospinal fluid Kiyoshi Takagi 1,2,3 , Shuichiro Asano 4 , Ryosuke Takagi 5 , Shuichiro Asano 3 , Shuichiro Asano 3 , Introduction: Brain computed tomography (CT) is an affordable and widely available modality. In idiopathic normal pressure hydrocephalus (iNPH), CT scans are used to assess ventricular enlargement and other morphological features. We aim to quantify the lateral ventricle volumes before and after shunt surgery in iNPH using automated CTbased volumetry, derived with a novel deep learning approach. Methods: We developed U-Net-based deep learning models to segment ventricular cerebrospinal fluid (VCSF) from CT images. We initialized the U-Net with transferable features from a pre-trained model trained to detect VCSF-related morphological features from magnetic resonance imaging-based VCSF labels. The U-Net was then trained to identify VCSF in CT images learning from manual segmentations. The training set comprised of 62 iNPH datasets and paired manual labels from Uppsala University Hospital, of which 23 patients had post-shunt scans with intraventricular catheters. Post model development, we evaluated the segmentation performance of deep-learning-derived VCSF against manual-VCSF as standard criterion. Results: In the iNPH training dataset (n = 62), high volumetric correlations of r = 0.94 were observed between automatically and manually derived VCSF. The volumetric correlations between automatically and manually derived VCSF in pre-(r = 0.98) and post-shunt images (r = 0.97) were similar. Conclusions: Preliminary results demonstrate strong potential for automated CT-derived VCSF volumetry in the assessment of iNPH, with comparable performance to manual segmentations. The model performed surprisingly well on scans with an intraventricular catheter. Future work will explore the model performance in a validation cohort, analyze volumetric changes after shunting, and explore additional aspects of diagnostic potential of automated CT-volumetry.